Frequently Asked Questions

I'm having trouble with Weblab. What should I do? First, read the User Manual and the rest of this document to see if your question has already been addressed. If it is not, submit a bug report by clicking on the "Report a Bug" link under the Service Broker's "Help" section.

Can I run the Weblab client on my computer running MAC OS X? Please see our System Requirements page for a list of tested and supported OS/browser configurations. UPDATE: There appears to be a problem with the current version of the iLab Service Broker that prevents the successful launch of the WebLab client on Mac platforms. We are looking into ways to solve this problem. In the meantime, please a tested platform listed in our System Requirements page.

I've clicked on the "Launch Client" Button and, after a reasonable amount of time, nothing has happened. What does this mean? The WebLab 6.1 graphical client requires that your web browser be configured with version 1.4.2 or greater of the Sun Java Plugin. If your browser is not properly configured, the applet will fail to launch when requested. If you encounter this problem, make sure you have downloaded and installed the latest version of the Java Plugin. Instructions for checking your browser's plugin configuration and downloading the Java Plugin can be found below.

I can log on and access the lab client. When I click "Launch Lab," the applet loads but I get the following error: "Server error: An I/O error occurred. Failed to load lab configuration. Try again?" This error can be caused by a number of different things. Some causes are:

  1. If you browse to the Service Broker using a URL other than that given to you. For example, if the Service Broker URL is http://ilab.mit.edu/, but you access the broker via http://ilab/ or by browsing to the IP address. In this case, the client will fail to initialize.
  2. If you log into the Service Broker and leave the session idle for approximately 30 minutes and then try to launch the client, the client will fail to initialize.
  3. If, at the security warning dialog that is presented while the client is loading, you click on the "No" button, the client will fail to initialize. This warning indicates that the client is requesting privileges above and beyond what is typical for a Java applet. These privileges are what enable the client to communicate with the Service Broker as well as save experiment results to your computer.
If none of these resolve the problem, please submit a bug report using the Service Broker's "Report a Bug" feature (located in the "Help" section). Be sure to include the following information:

How can I tell which version of the Java Plugin I have? Open the Java Console and scroll to the top of the window. The very first line should say something like "Using JRE version 1.5.0_04 Java HotSpot(TM) Client VM". If you see a version number that's less than 1.4.2, you need to install a new Java Plugin if you want to use the WebLab 6.1 client. .

How do I open the Java Console?
If you are using a Windows or Linux:

If you are using Mac OSX - Unfortunately, Mac OS X browsers do not give you a convenient menu item for displaying the Java console when you want to. In order to display the console, please perform the following configuration:

Open a Finder window. Select Applications (from the quick-access bar on the left), then browse to Utilities/Java/

You'll see two items called "Java 1.3.1 Plugin Settings" (if you are using Firefox) and/or "Java 1.4.2 Plugin Settings" (if you are using Safari) which control the settings of the respective plugins. Open each of them in turn, check the box for "Show Java Console" or "Use Java console", and close the settings box again. From now on, the Java console should automatically appear on the screen whenever you load an applet in your browser (note: you may need to quit your browser and restart it first).

If you can't find a "Java Console" menu option, you probably need to install a new Java Plugin.

Where can I download the Java Plugin? Go to http://java.sun.com/j2se/1.5.0/download.jsp (note: the link you want is "Download JRE 5.0 Update 4" under the in the "JRE 5.0 Update 4" section, about half way down the page)

Okay, I've read the documentation carefully, and I'm still having trouble. Now what? Submit a detailed bug report to the developers, and we'll get back to you as quickly as possible. To submit a bug report, click on the "Report a Bug" link under the Service Broker's "Help" section. Alternatively, you can email us directly at ilab-debug@mit.edu . However, using the "Report a Bug" feature will help us diagnose your problem faster.

What information should I include in my bug report? We try to monitor Weblab regularly and to address problems as they arise, so it is usually the case that everything is working pretty well as far as we know. Submitting a bug report that says nothing more than "X doesn't work" is therefore not likely to be particularly helpful, because in all probability we've tested X ourselves in the past and it has worked just fine for us. In order to help us figure out why it isn't working just fine for you, we need to know as much as possible about the problem.

A good bug report should include at least the following pieces of information:

If you encounter an error message, be sure to include the exact text of the error message in your bug report.

My experiment runs, and I think I have everything set up right, but the data looks not at all like what I expect. Check the compliance values carefully to make sure you haven’t set them too low. If a compliance value is exceeded during the measurement, this can have a major impact on the rest of the data points, and there is unfortunately no obvious way to tell when a compliance has been exceeded.